1. Field of the Invention:
This invention relates to a package to encapsulate an integrated circuit device (die). More particularly, this invention relates to a package having an exposed integrated circuit device and a method for the manufacture of such a package.
2. Description of the Related Art:
Molded plastic electronic packages provide environmental protection to integrated circuit devices. Packages such as the PQFP (plastic quad flat pack) and the PLCC (plastic leaded chip carrier) protect an encapsulated device from contaminants such as moisture and from mechanical shock.
One disadvantage with molded plastic packages is poor thermal dissipation. During operation, the integrated circuit device generates heat that must be removed to maintain the operating integrity of the device. Some heat is dissipated through the bonding wires and the lead frame, the remainder is absorbed into the molding resin. The molding resin is a poor thermal conductor so the device temperature increases. To prevent the device from overheating, the power provided to the device must be limited.
One way to increase thermal dissipation is to mount the backside of the integrated circuit device on to a metallic heat spreader. As disclosed in U.S. Pat. No. 5,608,267, this heat spreader may be only partially encapsulated into the molding resin to provide enhanced thermal dissipation. However, having a heat spreader to molding resin interface provides a source of ingress for moisture. Moisture migrates along the interface and causes internal metallic components to corrode. Also, when heated, the moisture may expand destroying the integrity of the molded plastic package. One solution, as disclosed in U.S. Pat. No. 6,188,130, is to incorporate features into the heat spreader to increase the distance moisture must travel to reach encapsulated components. Both the U.S. Pat. No. 5,608,267 patent and the U.S. Pat. No. 6,188,130 patent are incorporated by reference in their entireties herein.
While an exposed backside heat spreader enhances thermal dissipation, the thickness of the molded plastic package must be sufficient to partially encapsulate the heat spreader. In addition, there is a move towards packages with enhanced sensing capabilities, such as optical, thermal or mechanical sensing. The presence of a large metallic heat spreader interferes with the sensing capabilities.
There remains a need for a molded plastic package having the combination of effective thermal dissipation and good sensing capabilities that is further thinner than the present electronic packages. There further remains a need for a method to easily assemble such molded plastic packages.